1. Field of the Invention
The present invention relates to information storage media, and more particularly, to an information storage medium such as an optical disc supporting partial data replacement, a recording and/or reproducing apparatus and a recording and/or reproducing method.
2. Related Art
In general, a rewritable information storage medium contains a data area for storing data and management areas for storing information for data management. The data area is provided with a user data area for storing user data and at least one spare area for defect management. When user data is recorded in the user data area (an area in the data area that excludes the spare area), or when user data recorded in the user data area is reproduced and a defect is generated, replacement data to replace the defect data is recorded in the spare area.
In case of a write-once information storage medium, this defect management technique is used in connection with logical overwrite (LOW). Logical overwrite (LOW) is known as a method by which the write-once information storage medium can be used in the same manner as a rewritable information storage medium. That is, in order to update data already recorded in a user data area, the recorded data can be treated as if it is defect data, and data to replace this recorded data (which is treated as “defect data”) is recorded in a spare area. Thus, while the logical address of the data recorded in the user data area is fixed, the address of the data recorded in the spare area can be used as the physical address corresponding to the logical address. By doing so, a host can see data in the user data area as if only rewriting of the data is performed at the identical location, and therefore data management can be made easier and more effective. This is because the host uses only the logical addresses of data. However, the area used for recording replacement (update) date is limited to the spare area.
More recently, a new method which implements LOW for defect management is utilized to maximize the capacity of an information storage medium. In such a method, the area for recording updated data is not limited to the spare area, and updated data can also be recorded in an unrecorded area of the user data area of the information storage medium and replacement information (defect entry information) can be prepared accordingly.
Generally, in an information storage system, a host is used to manage data in units of sectors (each sector having 2048 bytes) and a drive system is used to record data on and reproduce data from an information storage medium in units of one or more sectors (for example, 16 sectors, or 32 sectors). When data is desired to be recorded or logically overwritten not in an entire block in an already recorded area on an information storage medium, but in some sectors in the area, the drive system first reproduces data in a block including the sectors in which the host commands the drive system to record data in the already recorded area, replaces the data corresponding to the sectors of the command with the data of the command by the host, and then records the data. This process is referred to as a read-modify-write (RMW). If an information storage medium is a rewritable information storage medium, data is overwritten in an identical physical location in the RMW process. If an information storage medium is a write-once information storage medium, data is replaced by the LOW process.
If a defect occurs during the RMW process in the rewritable information storage medium, that is, during data reproduction or during data writing after the read and modification of data occurred, the defect data need to be replaced. Thus, in order to indicate the state of the block replaced by the RMW process in a rewritable information storage medium or a write-once information storage medium, a replacement (defect) entry is generated. At this time, the drive system generally manages this replacement state by using replacement information indicating a state in which the block address corresponding to the original location is replaced by the address of the block replacing the original location. However, due to the replacement information in units of blocks, data reproduction can require significantly more time.
FIGS. 1A and 1B are reference diagrams of an example data area on an information storage medium and an example replacement (defect) entry used to illustrate conventional time delay problems during data reproduction.
Specifically, FIG. 1A illustrates an example data area 110 on an information storage medium 100, including a spare area #1 112, a user data area 114 and a spare area #2 116. FIG. 1A shows a state in which in order to update file B with file B′ (8 sectors) in a user data area 114 where file A (19 sectors), the file B (8 sectors) and file C (21 sectors) are contiguously recorded, a host sends a write command with the address at which the file B is recorded, and the drive system performs the RMV process and records part {circle around (A)} of the file A, part {circle around (B)} of the file B′, and part {circle around (C)} of the file C in physical sector number PSN 48˜PSN 63. Though the part that should be actually updated is the file B, data recording and data reproduction are performed by the drive system in units of blocks, and one block, i.e., the back part of the file A and the front part of the file C, is replaced.
FIG. 1B shows a replacement entry 120 in a replaced state. Referring to FIG. 1B, PSN 16 is stored in the original PSN 122 and PSN 48 is stored in the replacement PSN 124. As a result, a data block corresponding to PSN 16˜PSN 31 is replaced by a data block corresponding to PSN 48˜PSN 63.
In this state, if the host sends a read command in order to reproduce the file A recorded in logical sector number LSN 0˜LSN 18, the drive system first identifies a replacement state from the replacement (defect) entry 120 in order to reproduced PSN 0˜PSN 18. Then, the drive system reproduces the first block corresponding to PSN 0˜PSN 15, and then reproduces individual sectors inside the next data block corresponding to PSN 16˜PSN 18. At this time, the drive system learns from the replacement entry 120 that the data block corresponding to PSN 16˜PSN 31 is replaced by PSN 48˜PSN 63, reproduces the block corresponding to PSN 48˜PSN 63 and transmits replacement sectors PSN 48˜PSN 63 corresponding to PSN 16˜PSN 18 to the host. Thus, PSN 16˜PSN 18 of the file A are actually the sectors that are originally not needed to be replaced, and even though these sectors are replaced, the sectors in the original block and the replacement block are identical data. As a result, PSN 48˜PSN 50 in the replacement block is not necessarily needed to be reproduced. However, since the drive system does not know this situation, the drive system will continue to reproduce data in the replacement block as requested by the host such that more time is necessarily required for data reproduction.
So far, data replacement by LOW in the context of a write-once information storage medium is described with reference to FIGS. 1A-1B. However, the same problem occurs in a rewritable information storage medium. If PSN 16˜PSN 31 are regarded as a defect during a RMW process to update data B′, the data B′ is recorded in a spare area 112 or 116 as a substitute. Also at this time, if the host desires to reproduce file A, the drive system should reproduce the data from the replacement block in order to reproduce PSN 16˜PSN 18. However, in this case since the data recorded in the replacement block corresponding to PSN 16˜PSN 18 can be different from the data recorded in PSN 16˜PSN 18 in the original block, such a difference can cause data errors and other problems. This is because if an error occurs during a read operation of the RMW process, the drive system cannot reproduce data recorded in PSN 16˜PSN 31, and therefore updates data B′ only in PSN 19˜PSN 31 in response to a write command of the host, and fills padding data (00h) in the remaining area. Accordingly, there is a need for new techniques for use in a drive system in which data replacement by LOW is implemented in both a user data area and a spare data, or a drive system performing defect management to reduce, if not eliminate, the delay time during data reproduction, and thereby improving data reproduction performance.